The present invention relates to planar diaphragm type loudspeaker systems. More particularly, the invention relates to a loudspeaker system in which square planar diaphragms for bass-range, mid-range and treble-range are arranged coaxially.
It is known that a planar diaphragm has acoustic pressure characteristics relatively flat over a wide frequency range thus providing high fidelity sound reproduction. A variety of such type loudspeaker systems using planar diaphragms have been proposed in the prior art. In a conventional planar diaphragm type loudspeaker system, loudspeaker units adapted to reproduce bass, mid and treble ranges, respectively, have been separately mounted on a baffle board. One of the significant features of such a planar diaphragm type loudspeaker system resides in that the acoustic image scarcely shifts. In a multi-way, that is, a 2-way, 3-way and 4-way loudspeaker system, however, the above feature becomes more remarkable by arranging the diaphragms coaxially.
For this purpose, to assemble such a coaxial multi-way planar diaphragm type loudspeaker system, there is a problem in that it is difficult to arrange and assemble planar diaphragms of loudspeaker units covering all frequency ranges coaxially with the same ease as a loudspeaker system using cone-shaped diaphragms. That is, since the backside spaces of respective planar diaphragms are common, disadvantages that the backside pressure may cause interference and that the construction of a frame assembly supporting the planar diaphragms is complicated occur. Furthermore, in the case where planar diaphragm type loudspeaker units covering bass, mid, treble and further super-treble ranges are arranged coaxially, a difficulty in a backchamber provided for the mid-range diaphragm may occur. Since the planar diaphragm for the bass-range is arranged at an outermost side, a large opening aperture is required. Moreover, in the case where a backchamber for a mid-range loudspeaker unit having a large inner capacity is provided in the rear-side space of the bass-range planar loudspeaker unit whereby the rear-side space of the mid-range planar loudspeaker unit is separated from that of the bass unit, the bass-range planar diaphragm is subjected to a backside pressure caused by the backchamber when it is reciprocated. Therefore, the reciprocating movement thereof may be adversely interfered with.